Now listen to part of a lecture on this topic in a psychology class.

Here's an example…from my own life.

Before I started teaching, I worked as a research assistant in a laboratory… for a year.

Well, during my very first week on the job, I made a suggestion to my boss on how we could improve the way we were running an experiment.

My suggestion was a good one: the experiment was successful, and we got great results.

Anyway, that first week, because of that one experiment, my boss decided, perhaps without even realizing it…he decided I was a great research assistant.

And he never changed his mind.

After that first week, I was…I was okay, you know, average.

I was a good worker, but I also made mistakes—everyone does.

But whenever my boss introduced me to someone, he'd say: this is John, our star research assistant.

But a coworker of mine, she wasn't as fortunate.

Her first week at the lab, she made a big mistake and the lab lost some important data.

We recovered the data, but it cost the lab time and money.

Well, our boss concluded that week that my coworker was unreliable…incompetent.

And he continued to think that.

But actually, after that week, she turned out to be a good research assistant, probably better than me.

She made some other, small mistakes—like I said, everyone does.

But our boss thought of her as unreliable…'cause he only noticed her mistakes.